Method and system for ultrasound treatment of skin

ABSTRACT

Methods and systems for treating skin, such as stretch marks through deep tissue tightening with ultrasound are provided. An exemplary method and system comprise a therapeutic ultrasound system configured for providing ultrasound treatment to a shallow tissue region, such as a region comprising an epidermis, a dermis or a deep dermis. In accordance with various exemplary embodiments, a therapeutic ultrasound system can be configured to achieve depth with a conformal selective deposition of ultrasound energy without damaging an intervening tissue. In addition, a therapeutic ultrasound can also be configured in combination with ultrasound imaging or imaging/monitoring capabilities, either separately configured with imaging, therapy and monitoring systems or any level of integration thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/260,825 filed on Sep. 9, 2016, now U.S. Pat. No. 9,694,212, which isa continuation of U.S. patent application Ser. No. 14/554,668 filed onNov. 26, 2014, now U.S. Pat. No. 9,440,096, which is a continuation ofU.S. patent application Ser. No. 12/574,512 filed on Oct. 6, 2009, nowU.S. Pat. No. 8,915,870, which is a continuation of U.S. patentapplication Ser. No. 11/163,178, filed on Oct. 7, 2005, now U.S. Pat.No. 7,615,016 issued Nov. 10, 2009, which claims priority to and thebenefit of U.S. Provisional Application No. 60/617,338 filed on Oct. 7,2004, each of which are incorporated by reference in their entiretyherein. Any and all priority claims identified in the Application DataSheet, or any correction thereto, are hereby incorporated by referenceunder 37 CFR 1.57.

FIELD OF INVENTION

The present invention relates to ultrasound treatment systems, and inparticular to a method and system for treating stretch marks.

BACKGROUND OF THE INVENTION

Stretch marks, or striae disease, are the disfiguring permanent scarsleft in skin usually caused by excessive stretching such as during andafter rapid weight gain or pregnancy. These marks occur in 50-90% of allpregnant women, and usually appear in the later half of pregnancy asbright red or purplish lines. While the majority will be on the lowerabdomen they can also be found on the thighs, hips, buttocks, breastsand arms of women. During the postpartum period, the reddish linestypically turn into shallow silver scars.

Hydration of the skin via lotions and creams may help reduce thecreation of stretch marks and their effects in some cases, but cannotprevent them in women prone to the condition. Studies investigated theeffect of applying 0.1 percent tretinoin (retinoic acid or Retin-A)cream to stretch marks (S Kang et al. Topical tretinoin (retinoic acid)improves early stretch marks. Arch Dermatol 1996; 132:519-526.). Boththe length and width of the marks were diminished but side effectsinclude dry and itchy skin and moderate to severe erythema. Thistreatment works best when applied during the first few days postpartum;however, its effects on breastfeeding are not known. It is toxic andteratogenic, and should never be used during pregnancy.

Postpartum light treatment may be helpful to diminish the appearance ofstretch marks. For temporary cosmetic relief, ultraviolet light (UVA)exposure may be used to tan the lighter skin areas represented bystretch marks. In the limited cases where stretch marks are darker thanthe surrounding skin, intense pulsed light may be used to removepigment. Pulsed dye lasers are also used.

Patterns of thermal ablation to epidermis and/or dermis and/or fibrousfascia are effective for treatment of various skin conditions. Recently,“fractional photothermolysis” using mid-infrared lasers to produce amicroscopic array of thermal injury zones that include both epidermisand dermis was reported to be effective and well-tolerated for treatmentof skin remodeling. A primary advantage of fractional photothermolysisis that each zone of thermal injury is smaller than can be easily seenwith the unaided eye, and surrounded by a zone of healthy tissue thatinitiates a rapid healing response. Repeat treatments, which are welltolerated, can be performed until a desired result is obtained. However,similar to any light based treatment, fractional photothermolysis posesthe disadvantage that it is intrinsically limited to regions ofapproximately the upper 1 millimeter of skin, because light thatpropagates more than about 1 mm through skin has been multiplyscattered, and can no longer be focused or delivered effectively to thetreatment area. Stretch marks involve both superficial and deep layersof the dermis, as well as fibrous fascia. Therefore it is imperative totreat not only near the surface of skin, but all the way down to thedeep dermis and fibrous fascia.

SUMMARY OF THE INVENTION

A method and system for ultrasound treatment of stretch marks areprovided. An exemplary method and system are configured for treatingstretch marks with therapy only, therapy and monitoring, imaging andtherapy, or therapy, imaging, and monitoring using focused, unfocused,or defocused ultrasound at various spatial and temporal energy settingsfor targeted treatment of stretch marks and surrounding tissues.

In accordance with one embodiment of the present invention, a method andsystem are configured to produce regions of ablation within a treatmentzone in spatially defined patterns, rather than heating and destroyingthe entire volume of the target layer of tissue. In accordance anotherexemplary embodiment of the present invention, a method and system canbe configured to specifically aim such regions of ablation within atreatment zone, to occur at the same location as the stretch marks.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is particularly pointed out in theconcluding portion of the specification. The invention, however, both asto organization and method of operation, may best be understood byreference to the following description taken in conjunction with theaccompanying drawing figures, in which like parts may be referred to bylike numerals:

FIG. 1 illustrates a block diagram of an exemplary ultrasound treatmentsystem for treating stretch marks in accordance with an exemplaryembodiment of the present invention;

FIGS. 2A-2C illustrate a cross sectional diagrams of exemplary probesystems in accordance with exemplary embodiments of the presentinvention;

FIGS. 3A and 3B illustrate block diagrams of an exemplary control systemin accordance with exemplary embodiments of the present invention;

FIGS. 4A and 4B illustrate block diagrams of an exemplary probe systemin accordance with exemplary embodiments of the present invention;

FIG. 5 illustrates a cross-sectional diagram of an exemplary transducerin accordance with an exemplary embodiment of the present invention;

FIGS. 6A and 6B illustrate cross-sectional diagrams of an exemplarytransducer in accordance with exemplary embodiments of the presentinvention;

FIG. 7 illustrates exemplary transducer configurations for ultrasoundtreatment in accordance with various exemplary embodiments of thepresent invention;

FIGS. 8A and 8B illustrate cross-sectional diagrams of an exemplarytransducer in accordance with another exemplary embodiment of thepresent invention;

FIG. 9 illustrates an exemplary transducer configured as atwo-dimensional array for ultrasound treatment in accordance with anexemplary embodiment of the present invention;

FIGS. 10A-10F illustrate cross-sectional diagrams of exemplarytransducers in accordance with other exemplary embodiments of thepresent invention;

FIG. 11 illustrates a schematic diagram of an acoustic coupling andcooling system in accordance with an exemplary embodiment of the presentinvention;

FIG. 12 illustrates a block diagram of a treatment system comprising anultrasound treatment subsystem combined with additional subsystems andmethods of treatment monitoring and/or treatment imaging as well as asecondary treatment subsystem in accordance with an exemplary embodimentof the present invention; and

FIGS. 13A and 13B illustrate schematic diagrams of treatment regions inaccordance with exemplary embodiments of the present invention.

DETAILED DESCRIPTION

The present invention may be described herein in terms of variousfunctional components and processing steps. It should be appreciatedthat such components and steps may be realized by any number of hardwarecomponents configured to perform the specified functions. For example,the present invention may employ various medical treatment devices,visual imaging and display devices, input terminals and the like, whichmay carry out a variety of functions under the control of one or morecontrol systems or other control devices. In addition, the presentinvention may be practiced in any number of medical contexts and thatthe exemplary embodiments relating to a method and system for treatingstretch marks as described herein are merely indicative of exemplaryapplications for the invention. For example, the principles, featuresand methods discussed may be applied to any medical application.Further, various aspects of the present invention may be suitablyapplied to other applications.

In accordance with various aspects of the present invention, a methodand system for treating stretch marks are provided. For example, inaccordance with an exemplary embodiment, with reference to FIG. 1, anexemplary treatment system 100 configured to treat a region of interest106 comprises a control system 102, an imaging/therapy probe withacoustic coupling 104, and a display system 108. Control system 102 anddisplay system 108 can comprise various configurations for controllingprobe 102 and overall system 100 functionality, such as, for example, amicroprocessor with software and a plurality of input/output devices,system and devices for controlling electronic and/or mechanical scanningand/or multiplexing of transducers, a system for power delivery, systemsfor monitoring, systems for sensing the spatial position of the probeand/or transducers, and/or systems for handling user input and recordingtreatment results, among others. Imaging/therapy probe 104 can comprisevarious probe and/or transducer configurations. For example, probe 104can be configured for a combined dual-mode imaging/therapy transducer,coupled or co-housed imaging/therapy transducers, or simply a separatetherapy probe and an imaging probe.

Stretch marks reflect the separation of collagen in the dermis of theskin and damage to other tissue such as fibrous fascia and epidermis.Continuous stretching of tissue to its elastic limit and beyond causesdamage to skin and its structure. In accordance with an exemplaryembodiment, treatment system 100 is configured for treating thestructures within the epidermis, dermis, deep dermis, and/or fibrousfascia, which include the superficial fascia, deep fascia, and/or fascialata, by imaging of region of interest 106 for localization of thetreatment area and/or surrounding structures; delivering of ultrasoundenergy at a depth, distribution, timing, and/or energy level to achievethe desired therapeutic effect; and monitoring the treatment areabefore, during, and/or after therapy to plan and assess the resultsand/or provide feedback.

As to the treatment of stretch marks, connective tissue can bepermanently tightened by thermal treatment to temperatures about 60degrees C. which causes tissue to shrink immediately by approximately30% in length. Shrinkage of tissue results in tightening desired forcorrection of stretch marks. Treating through localized heating ofregions of stretch marks to temperatures of about 60-90° C., withoutsignificant damage to overlying, underlying, or surrounding tissue, aswell as the precise delivery of therapeutic energy to stretch marks andobtaining feedback from the region of interest before, during, and aftertreatment can be suitably accomplished through treatment system 100.Subsequent tightening of tissue in ROI 106 results in minimization ofstretch marks in the targeted region in ROI 106 and improved appearanceof the overlaying superficial layers of the skin.

To further illustrate an exemplary method and system 200, with referenceto FIG. 2A-2C. An exemplary method and system are configured withreference to FIG. 2A for first, imaging 222 and display 224 of theregion of interest 202 for localization of the treatment area andsurrounding structures, second, delivery of focused, unfocused, ordefocused ultrasound energy 220 at a depth, distribution, timing, andenergy level to achieve the desired therapeutic effect of thermalablation to treat stretch mark 232, and third to monitor the treatmentarea and surrounding structures before, during, and after therapy toplan and assess the results and/or provide feedback to control system206 and operator. Exemplary probe 204 and/or transducers can bemechanically and/or electronically scanned 226 to place treatment zonesover an extended area, and the treatment depth 220 can be adjustedbetween a range of approximately 0 to 10 mm, or the maximum depth of thestretch marks or deep dermis.

Exemplary transducer probe 204 can be configured to be suitablycontrolled and/or operated in various manners. For example, transducerprobe 204 may be configured for use within an ultrasound treatmentsystem, an ultrasound imaging system, an ultrasound monitoring system,and/or any combination of an ultrasound treatment, imaging and/ormonitoring system including motion control subsystems.

Control system 206 can be configured with one or more subsystems,processors, input devices, displays and/or the like. Display 208 may beconfigured to image and/or monitor ROI 202 and/or any particularsub-region within ROI 202. Display 208 can be configured fortwo-dimensional, three-dimensional, real-time, analog, digital and/orany other type of imaging. Exemplary embodiments of both control system206 and display 208 are described in greater detail herein.

Region of tissue 202 can comprise a superficial layer, such as, forexample the epidermis and/or dermis, subcutaneous fat, and/or muscle.Exemplary transducer system 200, can be configured to providecross-sectional two-dimensional imaging 222 of ROI 202, displayed as animage 224, with a controlled thermal lesion 220.

Exemplary ultrasound transducer probe 204 can be configured in variousmanners to provide various functions. For example, an ultrasound therapytransducer system can be configured for spatial control and/or temporalcontrol by changing the position of transducer, its drive frequency,focal depth, drive amplitude, and timing of the exemplary transducer. Inaccordance with various exemplary embodiments, transducer probe 204 canbe configured for spatial control, such as by changing the distance fromtransducer probe 204 to a reflecting surface, or changing the angles ofenergy focused or unfocused to tissue regions 202 and/or 220, and/orconfigured for temporal control, such as by controlling changes in thefrequency, drive amplitude and timing of transducer probe 204 throughcontrol system 206. As a result, changes in the location of thetreatment region, the shape and size and/or volume of the spot or regionof interest, as well as the thermal conditions, can be dynamicallycontrolled versus time.

In addition to the spatial control, control system 206 and/or transducerprobe 204 can also be configured for temporal control, such as throughadjustment and optimization of drive amplitude levels,frequency/waveform selections, and timing sequences and other energydrive characteristics to control the treatment of tissue. The spatialand/or temporal control can also be facilitated through open-loop andclosed-loop feedback arrangements, such as through the monitoring ofvarious positional and temporal characteristics.

In order to deliver energy to ROI 202, transducer probe 204 and/or anyother transducers can be mechanically and/or electronically scanned 226to place treatment zones over an extended area. In one embodiment, atreatment depth 220 can be adjusted between a range of approximately 0to 10 mm, or the maximum depth of the stretch marks or deep dermis. Bydelivering energy, transducer probe 204 may be driven at a selectedfrequency, a phased array may be driven with certain temporal and/orspatial distributions, a transducer may be configured with one or moretransduction elements to provide focused, defocused and/or planarenergy, and/or the transducer may be configured and/or driven in anyother ways hereinafter devised. Various embodiments of transducer probe204 are described in greater detail herein.

In one embodiment, imaging 222 component can comprise a display 224 ofROI 202 to facilitate localization of the treatment area and surroundingstructures. Energy 220 may be delivered to ROI 202 using transducerprobe 204 configured to deliver focused, unfocused, and/or defocusedultrasound energy 220 at one or more treatment parameters. Variousconfigurations of transducer probe 204 are disclosed herein. As usedherein, the phrase “treatment parameters” includes, for example, adepth, distribution, timing, and/or energy level used to achieve adesired therapeutic effect of thermal ablation to treat stretch mark232.

Monitoring can be achieved using one or more monitoring subsystems tomonitor the treatment area and/or surrounding structures before, during,and/or after therapy. These monitoring subsystems include control system206 and control system 206 subcomponents (described herein). Monitoringcan also be used to plan and assess the results and/or provide feedbackto control system 206 and/or the user. As used herein, the term user mayinclude a person, employee, doctor, nurse, and/or technician, utilizingany hardware and/or software of other control systems.

In accordance with another aspect of the present invention, withreference to FIG. 2B, an exemplary monitoring method may monitor thetemperature profile or other tissue parameters of the region of interest202 and/or treatment zone 220, such as attenuation, speed of sound, ormechanical properties such as stiffness and strain, and suitably adjustthe spatial and/or temporal characteristics and energy levels of theultrasound therapy transducer. The results of such monitoring methodsmay be indicated on display 208 by means of one-, two-, orthree-dimensional images of monitoring results 250, or may be as simpleas success or fail type indicator 252, or combinations thereof.Additional treatment monitoring methods may be based on one or more oftemperature, video, profilometry, and/or stiffness or strain gauges orany other suitable sensing method.

In accordance with another exemplary embodiment, with reference to FIG.2C, an expanded treatment region of interest 252 includes a combinationof tissues, such as subcutaneous fat/adipose tissue 216 and muscle 218,among others. A multiple of such tissues may be treated includingstretch marks in combination with at least one of epidermis 212, dermis214, adipose tissue 216, muscular fascia, muscle 218, hair, glands, andblood vessels within dermis 214, or other tissue of interest. Forexample, treatment 220 of stretch mark may be performed in combinationwith treatment of subcutaneous fat 216 by suitable adjustment of thetreatment parameters and/or transducers in probe 204.

As previously described, control systems 102 and 206 may be configuredin various manners with various subsystems and subcomponents. Withreference to FIGS. 3A and 3B, in accordance with exemplary embodiments,an exemplary control system 300 can be configured for coordination andcontrol of the entire therapeutic treatment process in accordance withthe adjustable settings made by a therapeutic treatment system user. Forexample, control system 300 can suitably comprise power sourcecomponents 302, sensing and monitoring components 304, cooling andcoupling controls 306, and/or processing and control logic components308. Control system 300 can be configured and optimized in a variety ofways with more or less subsystems and components to implement thetherapeutic system for treating stretch marks, and the embodiment inFIGS. 3A and 3B are merely for illustration purposes.

For example, for power sourcing components 302, control system 300 cancomprise one or more direct current (DC) power supplies 303 configuredto provide electrical energy for entire control system 300, includingpower required by a transducer electronic amplifier/driver 312. A DCcurrent sense device 305 can also be provided to confirm the level ofpower going into amplifiers/drivers 312 for safety and monitoringpurposes.

Amplifiers/drivers 312 can comprise multi-channel or single channelpower amplifiers and/or drivers. In accordance with an exemplaryembodiment for transducer array configurations, amplifiers/drivers 312can also be configured with a beamformer to facilitate array focusing.An exemplary beamformer can be electrically excited by anoscillator/digitally controlled waveform synthesizer 310 with relatedswitching logic.

The power sourcing components can also include various filteringconfigurations 314. For example, switchable harmonic filters and/ormatching may be used at the output of amplifier/driver 312 to increasethe drive efficiency and effectiveness. Power detection components 316may also be included to confirm appropriate operation and calibration.For example, electric power and other energy detection components 316may be used to monitor the amount of power going to an exemplary probesystem.

Various sensing and monitoring components 304 may also be suitablyimplemented within control system 300. For example, in accordance withan exemplary embodiment, monitoring, sensing and interface controlcomponents 324 may be configured to operate with various motiondetection systems implemented within transducer probe 104 to receive andprocess information such as acoustic or other spatial and temporalinformation from a region of interest. Sensing and monitoring componentscan also include various controls, interfacing and switches 309 and/orpower detectors 316. Such sensing and monitoring components 304 canfacilitate open-loop and/or closed-loop feedback systems withintreatment system 100.

For example, in such an open-loop system, a system user can suitablymonitor the imaging and/or other spatial or temporal parameters and thenadjust or modify same to accomplish a particular treatment objective.Instead of, or in combination with open-loop feedback configurations, anexemplary treatment system can comprise a closed-loop feedback system,wherein images and/or spatial/temporal parameters can be suitablymonitored within monitoring component to generate signals.

During operation of exemplary treatment system 100, a lesionconfiguration of a selected size, shape, orientation is determined.Based on that lesion configuration, one or more spatial parameters areselected, along with suitable temporal parameters, the combination ofwhich yields the desired conformal lesion. Operation of the transducercan then be initiated to provide the conformal lesion or lesions. Openand/or closed-loop feedback systems can also be implemented to monitorthe spatial and/or temporal characteristics, and/or other tissueparameter monitoring, to further control the conformal lesions.

Cooling/coupling control systems 306 may be provided to remove wasteheat from exemplary probe 104, provide a controlled temperature at thesuperficial tissue interface and deeper into tissue, and/or provideacoustic coupling from transducer probe 104 to region-of-interest 106.Such cooling/coupling control systems 306 can also be configured tooperate in both open-loop and/or closed-loop feedback arrangements withvarious coupling and feedback components.

Processing and control logic components 308 can comprise various systemprocessors and digital control logic 307, such as one or more ofmicrocontrollers, microprocessors, field-programmable gate arrays(FPGAs), computer boards, and associated components, including firmwareand control software 326, which interfaces to user controls andinterfacing circuits as well as input/output circuits and systems forcommunications, displays, interfacing, storage, documentation, and otheruseful functions. System software and firmware 326 controls allinitialization, timing, level setting, monitoring, safety monitoring,and all other system functions required to accomplish user-definedtreatment objectives. Further, various control switches 308 can also besuitably configured to control operation.

An exemplary transducer probe 104 can also be configured in variousmanners and comprise a number of reusable and/or disposable componentsand parts in various embodiments to facilitate its operation. Forexample, transducer probe 104 can be configured within any type oftransducer probe housing or arrangement for facilitating the coupling oftransducer to a tissue interface, with such housing comprising variousshapes, contours and configurations depending on the particulartreatment application. For example, in accordance with an exemplaryembodiment, transducer probe 104 can be depressed against a tissueinterface whereby blood perfusion is partially and/or wholly cut-off,and tissue flattened in superficial treatment region-of-interest 106.Transducer probe 104 can comprise any type of matching, such as forexample, electric matching, which may be electrically switchable;multiplexer circuits and/or aperture/element selection circuits; and/orprobe identification devices, to certify probe handle, electricmatching, transducer usage history and calibration, such as one or moreserial EEPROM (memories). Transducer probe 104 may also comprise cablesand connectors; motion mechanisms, motion sensors and encoders; thermalmonitoring sensors; and/or user control and status related switches, andindicators such as LEDs. For example, a motion mechanism in probe 104may be used to controllably create multiple lesions, or sensing of probemotion itself may be used to controllably create multiple lesions and/orstop creation of lesions, e.g. for safety reasons if probe 104 issuddenly jerked or is dropped. In addition, an external motion encoderarm may be used to hold the probe during use, whereby the spatialposition and attitude of probe 104 is sent to the control system to helpcontrollably create lesions. Furthermore, other sensing functionalitysuch as profilometers or other imaging modalities may be integrated intothe probe in accordance with various exemplary embodiments.

With reference to FIGS. 4A and 4B, in accordance with an exemplaryembodiment, a transducer probe 400 can comprise a control interface 402,a transducer 404, coupling components 406, and monitoring/sensingcomponents 408, and/or motion mechanism 410. However, transducer probe400 can be configured and optimized in a variety of ways with more orless parts and components to provide ultrasound energy for treatingstretch marks, and the embodiment in FIGS. 4A and 4B are merely forillustration purposes.

In accordance with an exemplary embodiment of the present invention,transducer probe 400 is configured to deliver energy over varyingtemporal and/or spatial distributions in order to provide energy effectsand initiate responses in a region of interest. These effects caninclude, for example, thermal, cavitational, hydrodynamic, and resonanceinduced tissue effects. For example, exemplary transducer probe 400 canbe operated under one or more frequency ranges to provide two or moreenergy effects and initiate one or more responses in the region ofinterest. In addition, transducer probe 400 can also be configured todeliver planar, defocused and/or focused energy to a region of interestto provide two or more energy effects and to initiate one or moreresponses. These responses can include, for example, diathermy,hemostasis, revascularization, angiogenesis, growth of interconnectivetissue, tissue reformation, ablation of existing tissue, proteinsynthesis and/or enhanced cell permeability. These and various otherexemplary embodiments for such combined ultrasound treatment, effectsand responses are more fully set forth in U.S. patent application Ser.No. 10/950,112, entitled “METHOD AND SYSTEM FOR COMBINED ULTRASOUNDTREATMENT,” Filed Sep. 24, 2004 and incorporated herein by reference.

Control interface 402 is configured for interfacing with control system300 to facilitate control of transducer probe 400. Control interfacecomponents 402 can comprise multiplexer/aperture select 424, switchableelectric matching networks 426, serial EEPROMs and/or other processingcomponents and matching and probe usage information 430 and interfaceconnectors 432.

Coupling components 406 can comprise various devices to facilitatecoupling of transducer probe 400 to a region of interest. For example,coupling components 406 can comprise cooling and acoustic couplingsystem 420 configured for acoustic coupling of ultrasound energy andsignals. Acoustic cooling/coupling system 420 with possible connectionssuch as manifolds may be utilized to couple sound into theregion-of-interest, control temperature at the interface and deeper intotissue, provide liquid-filled lens focusing, and/or to remove transducerwaste heat. Coupling system 420 may facilitate such coupling through useof various coupling mediums, including air and other gases, water andother fluids, gels, solids, and/or any combination thereof, or any othermedium that allows for signals to be transmitted between transduceractive elements 412 and a region of interest. In addition to providing acoupling function, in accordance with an exemplary embodiment, couplingsystem 420 can also be configured for providing temperature controlduring the treatment application. For example, coupling system 420 canbe configured for controlled cooling of an interface surface or regionbetween transducer probe 400 and a region of interest and beyond andbeyond by suitably controlling the temperature of the coupling medium.The suitable temperature for such coupling medium can be achieved invarious manners, and utilize various feedback systems, such asthermocouples, thermistors or any other device or system configured fortemperature measurement of a coupling medium. Such controlled coolingcan be configured to further facilitate spatial and/or thermal energycontrol of transducer probe 400.

In accordance with an exemplary embodiment, with additional reference toFIG. 11, acoustic coupling and cooling 1140 can be provided toacoustically couple energy and imaging signals from transducer probe1104 to and from the region of interest 1106, to provide thermal controlat the probe to region-of-interest interface 1110 and deeper into tissueand deeper into tissue, and to remove potential waste heat from thetransducer probe at region 1144. Temperature monitoring can be providedat the coupling interface via a thermal sensor 1146 to provide amechanism of temperature measurement 1148 and control via control system1102 and a thermal control system 1142. Thermal control may consist ofpassive cooling such as via heat sinks or natural conduction andconvection or via active cooling such as with peltier thermoelectriccoolers, refrigerants, or fluid-based systems comprised of pump, fluidreservoir, bubble detection, flow sensor, flow channels/tubing 1144 andthermal control 1142.

Monitoring and sensing components 408 can comprise various motion and/orposition sensors 416, temperature monitoring sensors 418, user controland feedback switches 414 and other like components for facilitatingcontrol by control system 300, e.g., to facilitate spatial and/ortemporal control through open-loop and closed-loop feedback arrangementsthat monitor various spatial and temporal characteristics.

Motion mechanism 410 can comprise manual operation, mechanicalarrangements, or some combination thereof. For example, a motionmechanism 422 can be suitably controlled by control system 300, such asthrough the use of accelerometers, encoders or otherposition/orientation devices 416 to determine and enable movement andpositions of transducer probe 400. Linear, rotational or variablemovement can be facilitated, e.g., those depending on the treatmentapplication and tissue contour surface.

Transducer 404 can comprise one or more transducers configured forproducing conformal lesions of thermal injury in superficial humantissue within a region of interest through precise spatial and temporalcontrol of acoustic energy deposition. Transducer 404 can also compriseone or more transduction elements and/or lenses 412. The transductionelements can comprise a piezoelectrically active material, such as leadzirconante titanate (PZT), or any other piezoelectrically activematerial, such as a piezoelectric ceramic, crystal, plastic, and/orcomposite materials, as well as lithium niobate, lead titanate, bariumtitanate, and/or lead metaniobate. In addition to, or instead of, apiezoelectrically active material, transducer 404 can comprise any othermaterials configured for generating radiation and/or acoustical energy.Transducer 404 can also comprise one or more matching layers configuredalong with the transduction element such as coupled to thepiezoelectrically active material. Acoustic matching layers and/ordamping may be employed as necessary to achieve the desiredelectroacoustic response.

In accordance with an exemplary embodiment, the thickness of thetransduction element of transducer 404 can be configured to be uniform.That is, a transduction element 412 can be configured to have athickness that is substantially the same throughout. In accordance withanother exemplary embodiment, the thickness of a transduction element412 can also be configured to be variable. For example, transductionelement(s) 412 of transducer 404 can be configured to have a firstthickness selected to provide a center operating frequency ofapproximately 2 MHz to 50 MHz, such as for imaging applications.Transduction element 412 can also be configured with a second thicknessselected to provide a center operating frequency of approximately 2 to50 MHz, and typically between 5 MHz and 25 MHz for therapy application.Transducer 404 can be configured as a single broadband transducerexcited with at least two or more frequencies to provide an adequateoutput for generating a desired response. Transducer 404 can also beconfigured as two or more individual transducers, wherein eachtransducer comprises one or more transduction element. The thickness ofthe transduction elements can be configured to provide center-operatingfrequencies in a desired treatment range.

Transducer 404 may be composed of one or more individual transducers inany combination of focused, planar, or unfocused single-element,multi-element, or array transducers, including 1-D, 2-D, and annulararrays; linear, curvilinear, sector, or spherical arrays; spherically,cylindrically, and/or electronically focused, defocused, and/or lensedsources. For example, with reference to an exemplary embodiment depictedin FIG. 5, transducer 500 can be configured as an acoustic array tofacilitate phase focusing. That is, transducer 500 can be configured asan array of electronic apertures that may be operated by a variety ofphases via variable electronic time delays. By the term “operated,” theelectronic apertures of transducer 500 may be manipulated, driven, used,and/or configured to produce and/or deliver an energy beam correspondingto the phase variation caused by the electronic time delay. For example,these phase variations can be used to deliver defocused beams, planarbeams, and/or focused beams, each of which may be used in combination toachieve different physiological effects in a region of interest 510.Transducer 500 may additionally comprise any software and/or otherhardware for generating, producing and/or driving a phased aperturearray with one or more electronic time delays.

Transducer 500 can also be configured to provide focused treatment toone or more regions of interest using various frequencies. In order toprovide focused treatment, transducer 500 can be configured with one ormore variable depth devices to facilitate treatment. For example,transducer 500 may be configured with variable depth devices disclosedin U.S. patent application Ser. No. 10/944,500, entitled “System andMethod for Variable Depth Ultrasound”, filed on Sep. 16, 2004, having atleast one common inventor and a common Assignee as the presentapplication, and incorporated herein by reference. In addition,transducer 500 can also be configured to treat one or more additionalROI 510 through the enabling of sub-harmonics or pulse-echo imaging, asdisclosed in U.S. patent application Ser. No. 10/944,499, entitled“Method and System for Ultrasound Treatment with a Multi-directionalTransducer”, filed on Sep. 16, 2004, having at least one common inventorand a common Assignee as the present application, and also incorporatedherein by reference.

Moreover, any variety of mechanical lenses or variable focus lenses,e.g. liquid-filled lenses, may also be used to focus and/or defocus thesound field. For example, with reference to exemplary embodimentsdepicted in FIGS. 6A and 6B, transducer 600 may also be configured withan electronic focusing array 604 in combination with one or moretransduction elements 606 to facilitate increased flexibility intreating ROI 610. Array 604 may be configured in a manner similar totransducer 502. That is, array 604 can be configured as an array ofelectronic apertures that may be operated by a variety of phases viavariable electronic time delays, for example, T₁, T₂ . . . T_(j). By theterm “operated,” the electronic apertures of array 604 may bemanipulated, driven, used, and/or configured to produce and/or deliverenergy in a manner corresponding to the phase variation caused by theelectronic time delay. For example, these phase variations can be usedto deliver defocused beams, planar beams, and/or focused beams, each ofwhich may be used in combination to achieve different physiologicaleffects in ROI 610.

Transduction elements 606 may be configured to be concave, convex,and/or planar. For example, in an exemplary embodiment depicted in FIG.6A, transduction elements 606A are configured to be concave in order toprovide focused energy for treatment of ROI 610. Additional embodimentsare disclosed in U.S. patent application Ser. No. 10/944,500, entitled“Variable Depth Transducer System and Method”, and again incorporatedherein by reference.

In another exemplary embodiment, depicted in FIG. 6B, transductionelements 606B can be configured to be substantially flat in order toprovide substantially uniform energy to ROI 610. While FIGS. 6A and 6Bdepict exemplary embodiments with transduction elements 604 configuredas concave and substantially flat, respectively, transduction elements604 can be configured to be concave, convex, and/or substantially flat.In addition, transduction elements 604 can be configured to be anycombination of concave, convex, and/or substantially flat structures.For example, a first transduction element can be configured to beconcave, while a second transduction element can be configured to besubstantially flat.

With reference to FIGS. 8A and 8B, transducer 404 can be configured assingle-element arrays, wherein a single-element 802, e.g., atransduction element of various structures and materials, can beconfigured with a plurality of masks 804, such masks comprising ceramic,metal or any other material or structure for masking or altering energydistribution from element 802, creating an array of energy distributions808. Masks 804 can be coupled directly to element 802 or separated by astandoff 806, such as any suitably solid or liquid material.

An exemplary transducer 404 can also be configured as an annular arrayto provide planar, focused and/or defocused acoustical energy. Forexample, with reference to FIGS. 10A and 10B, in accordance with anexemplary embodiment, an annular array 1000 can comprise a plurality ofrings 1012, 1014, 1016 to N. Rings 1012, 1014, 1016 to N can bemechanically and electrically isolated into a set of individualelements, and can create planar, focused, or defocused waves. Forexample, such waves can be centered on-axis, such as by methods ofadjusting corresponding transmit and/or receive delays, τ₁, τ₂, τ₃ . . .τ_(N). An electronic focus can be suitably moved along various depthpositions, and can enable variable strength or beam tightness, while anelectronic defocus can have varying amounts of defocusing. In accordancewith an exemplary embodiment, a lens and/or convex or concave shapedannular array 1000 can also be provided to aid focusing or defocusingsuch that any time differential delays can be reduced. Movement ofannular array 1000 in one, two or three-dimensions, or along any path,such as through use of probes and/or any conventional robotic armmechanisms, may be implemented to scan and/or treat a volume or anycorresponding space within a region of interest.

Transducer 404 can also be configured in other annular or non-arrayconfigurations for imaging/therapy functions. For example, withreference to FIGS. 10C-10F, a transducer can comprise an imaging element1012 configured with therapy element(s) 1014. Elements 1012 and 1014 cancomprise a single-transduction element, e.g., a combinedimaging/transducer element, or separate elements, can be electricallyisolated 1022 within the same transduction element or between separateimaging and therapy elements, and/or can comprise standoff 1024 or othermatching layers, or any combination thereof. For example, withparticular reference to FIG. 10F, a transducer can comprise an imagingelement 1012 having a surface 1028 configured for focusing, defocusingor planar energy distribution, with therapy elements 1014 including astepped-configuration lens configured for focusing, defocusing, orplanar energy distribution.

In accordance with another aspect of the invention, transducer probe 400may be configured to provide one, two or three-dimensional treatmentapplications for focusing acoustic energy to one or more regions ofinterest. For example, as discussed above, transducer probe 400 can besuitably diced to form a one-dimensional array, e.g., a transducercomprising a single array of sub-transduction elements.

In accordance with another exemplary embodiment, transducer probe 400may be suitably diced in two-dimensions to form a two-dimensional array.For example, with reference to FIG. 9, an exemplary two-dimensionalarray 900 can be suitably diced into a plurality of two-dimensionalportions 902. Two-dimensional portions 902 can be suitably configured tofocus on the treatment region at a certain depth, and thus providerespective slices 904 of the treatment region. As a result, thetwo-dimensional array 900 can provide a two-dimensional slicing of theimage place of a treatment region, thus providing two-dimensionaltreatment.

In accordance with another exemplary embodiment, transducer probe 400may be suitably configured to provide three-dimensional treatment. Forexample, to provide three dimensional treatment of a region of interest,with reference again to FIG. 3, a three-dimensional system can comprisetransducer probe 400 configured with an adaptive algorithm, such as, forexample, one utilizing three-dimensional graphic software, contained ina control system, such as control system 300. The adaptive algorithm issuitably configured to receive two-dimensional imaging, temperatureand/or treatment information relating to the region of interest, processthe received information, and then provide correspondingthree-dimensional imaging, temperature and/or treatment information.

In accordance with an exemplary embodiment, with reference again to FIG.9, an exemplary three-dimensional system can comprise a two-dimensionalarray 900 configured with an adaptive algorithm to suitably receive 904slices from different image planes of the treatment region, process thereceived information, and then provide volumetric information 906, e.g.,three-dimensional imaging, temperature and/or treatment information.Moreover, after processing the received information with the adaptivealgorithm, the two-dimensional array 900 may suitably providetherapeutic heating to the volumetric region 906 as desired.

Alternatively, rather than utilizing an adaptive algorithm, such asthree-dimensional software, to provide three-dimensional imaging and/ortemperature information, an exemplary three-dimensional system cancomprise a single transducer 404 configured within a probe arrangementto operate from various rotational and/or translational positionsrelative to a target region.

To further illustrate the various structures for transducer 404, withreference to FIG. 7, ultrasound therapy transducer 700 can be configuredfor a single focus, an array of foci, a locus of foci, a line focus,and/or diffraction patterns. Transducer 700 can also comprise singleelements, multiple elements, annular arrays, one-, two-, orthree-dimensional arrays, broadband transducers, and/or combinationsthereof, with or without lenses, acoustic components, and mechanicaland/or electronic focusing. Transducers configured as sphericallyfocused single elements 702, annular arrays 704, annular arrays withdamped regions 706, line focused single elements 708, 1-D linear arrays710, 1-D curvilinear arrays in concave or convex form, with or withoutelevation focusing, 2-D arrays, and 3-D spatial arrangements oftransducers may be used to perform therapy and/or imaging and acousticmonitoring functions. For any transducer configuration, focusing and/ordefocusing may be in one plane or two planes via mechanical focus 720,convex lens 722, concave lens 724, compound or multiple lenses 726,planar form 728, or stepped form, such as illustrated in FIG. 10F. Anytransducer or combination of transducers may be utilized for treatment.For example, an annular transducer may be used with an outer portiondedicated to therapy and the inner disk dedicated to broadband imagingwherein such imaging transducer and therapy transducer have differentacoustic lenses and design, such as illustrated in FIG. 10C-10F.

Various shaped treatment lesions can be produced using the variousacoustic lenses and designs in FIGS. 10A-10F. For example, cigar-shapedlesions may be produced from a spherically focused source, and/or planarlesions from a flat source. Concave planar sources and arrays canproduce a “V-shaped” or ellipsoidal lesion. Electronic arrays, such as alinear array, can produce defocused, planar, or focused acoustic beamsthat may be employed to form a wide variety of additional lesion shapesat various depths. An array may be employed alone or in conjunction withone or more planar or focused transducers. Such transducers and arraysin combination produce a very wide range of acoustic fields and theirassociated benefits. A fixed focus and/or variable focus lens or lensesmay be used to further increase treatment flexibility. A convex-shapedlens, with acoustic velocity less than that of superficial tissue, maybe utilized, such as a liquid-filled lens, gel-filled or solid gel lens,rubber or composite lens, with adequate power handling capacity; or aconcave-shaped, low profile, lens may be utilized and composed of anymaterial or composite with velocity greater than that of tissue. Whilethe structure of transducer source and configuration can facilitate aparticular shaped lesion as suggested above, such structures are notlimited to those particular shapes as the other spatial parameters, aswell as the temporal parameters, can facilitate additional shapes withinany transducer structure and source.

Through operation of ultrasound system 100, a method for treatingstretch marks can be realized that can facilitate effective andefficient therapy without creating chronic injury to human tissue. Forexample, a user may first select one or more transducer probeconfigurations for treating a region of interest. The user may selectany probe configuration described herein. Because the treatment regionranges from approximately 0 mm to 1 cm, exemplary transducer probes mayinclude, for example, an annular array, a variable depth transducer, amechanically moveable transducer, a cylindrical-shaped transducer, alinear array, a single element transducer and the like. As used herein,the term user may include a person, employee, doctor, nurse, and/ortechnician, utilizing any hardware and/or software of other controlsystems.

Once one or more transducers are selected, the user may then image aregion of interest in order to plan a treatment protocol. By imaging aregion of interest, the user may user the same treatment transducerprobe and/or one or more additional transducers to image the region ofinterest at a high resolution. In one embodiment, the transducer may beconfigured to facilitate high speed imaging over a large region ofinterest to enable accurate imaging over a large region of interest. Inanother embodiment, ultrasound imaging may include the use of Dopplerflow monitoring and/or color flow monitoring. In addition other means ofimaging such as MRI, X-Ray, PET, infrared or others can be utilizedseparately or in combination for imaging and feedback of the superficialtissue and the vascular tissue in the region of interest.

In accordance with another exemplary embodiment, with reference to FIG.12, an exemplary treatment system 200 can be configured with and/orcombined with various auxiliary systems to provide additional functions.For example, an exemplary treatment system 1200 for treating a region ofinterest 1206 can comprise a control system 1202, a probe 1204, and adisplay 1208. Treatment system 1200 further comprises an auxiliaryimaging modality 1274 and/or auxiliary monitoring modality 1272 may bebased upon at least one of photography and other visual optical methods,magnetic resonance imaging (MRI), computed tomography (CT), opticalcoherence tomography (OCT), electromagnetic, microwave, or radiofrequency (RF) methods, positron emission tomography (PET), infrared,ultrasound, acoustic, or any other suitable method of visualization,localization, or monitoring of stretch marks within region-of-interest1206, including imaging/monitoring enhancements. Such imaging/monitoringenhancement for ultrasound imaging via probe 1204 and control system1202 could comprise M-mode, persistence, filtering, color, Doppler, andharmonic imaging among others; furthermore an ultrasound treatmentsystem 1270, as a primary source of treatment, may be combined with asecondary source of treatment 1276, including radio frequency (RF),intense pulsed light (IPL), laser, infrared laser, microwave, or anyother suitable energy source.

By planning a treatment protocol, the user may choose one or morespatial and/or temporal characteristics to provide conformal ultrasoundenergy to a region of interest. For example, the user may select one ormore spatial characteristics to control, including, for example, the useone or more transducers, one or more mechanical and/or electronicfocusing mechanisms, one or more transduction elements, one or moreplacement locations of the transducer relative to the region ofinterest, one or more feedback systems, one or more mechanical arms, oneor more orientations of the transducer, one or more temperatures oftreatment, one or more coupling mechanisms and/or the like.

In one exemplary embodiment, ablation of stretch marks and surroundingtissues to temperatures greater than about 60 C, is utilized. In orderto facilitate producing arrays of small thermal injury zones, anultrasound transducer can be configured to propagate energy as a wavewith relatively little scattering, over depths up to many centimeters intissue depending on the ultrasound frequency. Depending on the size ofthe stretch mark to be treated, the treatment zone size can be achievedby varying the ultrasound wavelength. Because attenuation (absorption,mainly) of ultrasound by tissue increases with frequency, use of lowerfrequency ultrasound can maximize treatment efficiency.

In addition, the user may choose one or more temporal characteristics tocontrol in order to facilitate treatment of the region of interest. Forexample, the user may select and/or vary the treatment time, frequency,power, energy, amplitude and/or the like in order to facilitate temporalcontrol. For more information on selecting and controlling ultrasoundspatial and temporal characteristics, see U.S. application Ser. No.11/163,148, entitled “Method and System for Controlled Thermal Injury,”filed Oct. 6, 2005 and previously incorporated herein by reference.

After planning of a treatment protocol is complete, the treatmentprotocol can be implemented. That is, a transducer system can be used todeliver ultrasound energy to a treatment region to ablate select tissuein order to treat stretch marks. By delivering energy, the transducermay be driven at a select frequency, a phased array may be driven withcertain temporal and/or spatial distributions, a transducer may beconfigured with one or more transduction elements to provide focused,defocused and/or planar energy, and/or the transducer may be configuredand/or driven in any other ways hereinafter devised.

For example and in accordance with another aspect of the presentinvention, and with reference to an exemplary embodiment depicted inFIG. 13A, one or more treated zones 1340 are configured to produceregions of ablation within a treatment volume in spatially definedpatterns. These spatially defined patterns include, for example, adiscrete locus of treatment spots and/or a one- two- and/orthree-dimensional matrix of damage. These spatially defined patterns maybe desired rather than heating and destroying an entire volume of thetissue. In such a treatment the surrounding undamaged tissue aids rapidhealing and recovery.

Transducer probe 204 and/or any other transducers (not shown) can bemechanically and/or electronically scanned 1326 to extend the treatmentzone over a large area, and transducer probe 204 can be further scannedor moved 1328 to further enlarge the treatment zone. The zones oftreatment may be placed at depths ranging from approximately 0 to 10 mm,or the maximum depth of the stretch marks or deep dermis. Treatmentzones can run parallel and/or perpendicular to stretch marks and/orsurrounding tissue to create anisotropic patterns of tissue damage,and/or can cover a two-dimensional matrix extending over the disfiguringpattern of stretch marks.

In accordance with another aspect of the present invention, and withreference to an exemplary embodiment illustrated in FIG. 13B, a treatedzone 1360 may extend throughout regions of the dermis, and may evenextend to the epidermis 1362. In addition as treated zone 1360 increasesin depth, its cross section may increase from a small size 1364 (about asub millimeter) in a shallow region near or at the epidermis, to amedium size 1366 (about a sub millimeter to a millimeter) in a middlezone near and/or at the mid dermis, to large size 1368 (about amillimeter) in deep zones near and/or at the deep dermis. Furthermore asingle treated zone can have a shape expanding in cross section withdepth, and/or be composed of the fusion of several smaller treatmentzones. Spacing of treatment zones can be on the order of the treatmentzone size or zones or macro-zones may be fused together horizontally.The ultrasound beam can be spatially and/or temporally controlled bychanging the position of the transducer, its frequency, treatment depth,drive amplitude, and timing via the control system. (See, for example,U.S. application Ser. No. 10/163,148, filed on Oct. 6, 2005, andentitled METHOD AND SYSTEM FOR CONTROLLED THERMAL INJURY, herebyincorporated by reference).

Upon treatment, the steps outlined above can be repeated one or moreadditional times to provide for optimal treatment results. Differentablation sizes and shapes may affect the recovery time and time betweentreatments. For example, in general, the larger the surface area of thetreatment lesion, the faster the recovery. The series of treatments canalso enable the user to tailor additional treatments in response to apatient's responses to the ultrasound treatment.

The present invention may be described herein in terms of variousfunctional components and processing steps. It should be appreciatedthat such components and steps may be realized by any number of hardwarecomponents configured to perform the specified functions. For example,the present invention may employ various medical treatment devices,visual imaging and display devices, input terminals and the like, whichmay carry out a variety of functions under the control of one or morecontrol systems or other control devices. In addition, the presentinvention may be practiced in any number of medical contexts and thatthe exemplary embodiments relating to a system as described herein aremerely indicative of exemplary applications for the invention. Forexample, the principles, features and methods discussed may be appliedto any medical application. Further, various aspects of the presentinvention may be suitably applied to other applications, such as othermedical or industrial applications.

1. A method for treating stretch marks in skin, said method comprising:identifying a region of interest corresponding to a stretch mark in askin surface, said region of interest comprising at least a portion ofdermis, fibrous fascia, and subcutaneous fat; directing ultrasoundenergy into said region of interest heating a portion of said region ofinterest; treating at least a portion of said stretch mark; and treatingsaid subcutaneous fat.